It is well known in the art to use different lifting mechanisms in scaffoldings. Known scaffolding systems, and other types of load displacement systems, include a work platform or the like that is displaceable along a tower or the like.
Some towers support a plurality of work platforms, each carrying its own lifting mechanism. Furthermore, when the uppermost work platform needs to go back down, all platforms underneath obviously need to go down first, which is relatively expensive and inefficient. Most of the lifting mechanisms offer relatively slow platform displacement speeds in the order of a few (about 2 to 5) feet per minutes (about 0.6 to 1.5 meters per minute) which is really time consuming when the platform needs to be raised at and lowered from a few hundred feet high. Furthermore, the lifting mechanisms usually need additional safety mechanisms to prevent any possible free fall of the platforms. Lifting mechanisms using rollers meshing with a worm screw are subject to surface wear at the contacting interface there between and are limited to their loading capacity by the roller shafts and their support bearings. Furthermore, they suffer drawbacks from the tedious alignment of the rollers required in assembly. Also, in the event of shaft rupture, the platform risks to simply fall down until a safety mechanism is activated, thereby providing a braking shock and possible injuries or other types of subsequent failures.
Load displacement mechanisms that use balls into conventional ball screw systems as load carriers are typically expensive to manufacture and in maintenance. Accordingly, the balls of the ball screw circulate inside a loop that circles around at least one complete turn (360°) of the screw thread in a cycle fashion; which is relatively complex in manufacturing.
Other bearing systems, as disclosed by Sievert in U.S. Statutory Invention Registration No. H1384 published on Dec. 6, 1994, has a continuous bearing with the load bearing balls undergoing extensive shear loads instead of compressive loads, which would not be acceptable in case of failure. Furthermore, the bearing of Sievert is made to work in reciprocating displacement with the bearing balls never circling along the entire ball receptacle loop, which would be prevented by the balls jamming therein (because of a tendency of a ball to start rolling over or under a preceding ball—zig-zag phenomenon), and with the exposed balls being prevented from falling off by a race of the outer bail (moving part). Additionally, each ball of Sievert's bearing would not be capable of sustaining on its own without any damage a charge weighing many tons as would be the case in most load displacement systems.
Accordingly, there is a need for an improved load displacement apparatus with a simple configuration and improved components used therefor.